I 


TP 140 
.G4 P35 


. 1 








' ' •- 
















8 










>('- \ y ( Hi Of) i C,n . of 
















1 \ ])oi 11nei i \nt -Uaiti ( 1 c*t\ re 

AUG 1 1918 


I 









































































/ 







.iliV ; 






y 




•"V,* 




Ctils address toas delivered before tbe American academy of 5lrt^ 
and Sciences on tije occasion of ti )t presentation of ttje 
&umford Jttedal to tbe author for bte electric 
furnace products 


/°J, _ 4 ! 







an# la 3tclt atnufibfl astr/ sM'i> 

t(ti Id «ta}ir>?«ni.aiq tit lo noja&^Q nit »w em*fc£? d.*a 
jbttxh aRI to: iGiftafc vh at I&Gi&i * 
amrfltnq warn a j 



















SEVENTEEN YEARS 


OF 

Experimental Research 
and Development 


by 

EDWARD GOODRICH ACHESON 

of 

NIAGARA FALLS, N. Y. 



Before the 

American Academy of Arts and Sciences 

BOSTON, MASS., APRIL 8, 1908 




>• 





' t- 









Seventeen Years 0/Experimental 
Research and Development 

HILE the investigations and developments 
I am about to describe covered almost 
exactly seventeen years, the cause of my 
having entered into them was the realiza¬ 
tion of the great value of abrasive materials 
to the industrial world as the result of a 
remark made to me in the latter part of the 
year 1880 by Dr. George F. Kunz. The subject was 
again brought to mind in 1886, when in making an 
experiment I passed a quantity of hydro-carbon gas over 
highly heated clay articles, and observed that the clay 
became impregnated with carbon, and I thought it was 
increased in hardness by the presence of the carbon. 

In the month of March, 1891, having at my com¬ 
mand an electric generating plant of considerable 
capacity, and looking about for a line of experiments, I 
thought to try the impregnating of clay with carbon 
under the influence of the high heat obtainable with the 
electric current, and the production of an abrasive 
material. I mixed together a quantity of clay and 
powdered coke, placed the mixture in an iron bowl such 
as plumbers use for holding their melted solder. Into 
this mixture I inserted one end of an electric lamp 
carbon, the other end being connected to one lead from 
a dynamo, the other lead being attached to the iron 
bowl. A good strong current was sent through the 
mixture until the central portion of the clay was 
thoroughly melted and raised to a very high temperature. 
When cold the mass was removed and examined care¬ 
fully. Adhering to the end of the carbon rod, I noticed 
a few small bright specks. With difficulty I secured 
one, and placing it on the end of a lead pencil, drew it 
across a pane of glass. It not only scratched, but cut 
the glass. 



page three 










Appreciating the possible value of my discovery, 
and notwithstanding the exceedingly minute quantity of 
crystals produced, I undertook further experiments, and, 
if I am not mistaken, two months had passed before I 
had enough crystals to fill a small vial measuring about 
three-eighths by one inch. Naturally, I early undertook 
to prove its value as an abrasive. I mounted an iron disc 
in a lathe, charged its surface with oil and my new, then 
unnamed product, and with this revolving disc cut the 
polished face off a diamond. 

Having filled my little vial, I placed it in my vest 
pocket and went to New York, where I had a diamond- 
cutter use some of my new material for the re-polishing 
of the diamond. I had named it while on the way to New 
York. I called it Carborundum, under the belief that it 
contained carbon and corundum. The diamond-cutter 
bought what was left of the material at the price of 
thirty cents per carat, and with the proceeds I purchased 
a microscope to assist me in the further study of the 
material. 

Soon after this I learned that it was the silica in the 
clay, and not the alumina that was associating itself 
with the carbon, the chemical formula of the crystals 
being SiC, and I ceased using the clay, having sub¬ 
stituted sand. 

I had devised an electric furnace in which a resistant 
material formed a central core, around which was placed 
the material to be heated, and this probably was the 
->» first furnace wherein thermal and chemical effects were 
produced within the mass of material operated upon, the 
outer portions of the mass acting as retaining walls. It 
is thus that we can work at higher temperatures than 
would be possible were we required to depend upon the 
furnace walls proper. With this furnace I conducted 
experiments with many materials, among them being a 
mixture of lime and carbon. My original application for 
a United States patent, specified not only the carbide of 
silicon, but also of calcium. The patent as issued was, 
however, limited to the former, while a patent for the 
latter was afterward secured by a later experimenter. 


page four 


In 1894, The Carborundum Company, a company I 
had formed to develop the business, was located at 
Monongahela City, in western Pennsylvania, and was 
operating a plant of 134 horse-power. The cost of 
production was so high that the trade was restricted to 
lapidaries, valve grinding, and kindred lines that could 
afford to buy it, and but one-half its production was 
sold. The new electrical development at Niagara Falls 
was at this time approaching completion. I went to 
Niagara Falls, looked over the situation, possibilities 
and prices. On my return I convened a meeting of my 
Board of Directors and laid before them a scheme of 
moving to Niagara Falls, and there building and 
equipping a plant for 1,000 horse-power. 

To build a plant for 1,000 horse-power, in view of 
the fact that we were only selling one-half of the output 
from a 134 horse-power one, was a trifle too much for 
my conservative directors, and they one and all resigned. 
Fortunately, I was in control of the destiny of The 
Carborundum Company. I organized a new board, 
proceeded with my plans, and in the year 1904, the 
thirteenth one from the date of the discovery, The Carbo¬ 
rundum Company had a plant equipped with 5,000 
electrical horse - power, and produced over 7,000,000 
pounds of those specks I had picked off the end of the 
electric lamp carbon in the spring of 1891. 

Early in the history of its manufacture, I discovered 
that when Carborundum was heated to a very high 
temperature, decomposition occurred, the contained 
silicon was dissipated in vapor and a beautiful graphite 
left as a pseudomorph, or as I was pleased to call it, a 
skeleton of the original carborundum crystal. This 
discovery started me on a new line of thought, and as a 
result of a long series of experiments, the present 
methods of the International Acheson Graphite Company, 
a corporation I formed to carry on the business, were 
perfected. 

The graphite produced as the results of the decom¬ 
position of Carborundum is very soft and of a high 
metallic lustre, and my first efforts to produce graphite 


page five 


from comparatively pure carbon, I believed to be pro¬ 
ductive of failure, owing to the lack of lustre, softness 
and unctuous character. In fact, I was at that time of 
the opinion that it was not possible to produce a direct 
conversion of non-graphitic amorphous carbon into a 
graphitic carbon unless the carbon contained metallic 
impurities. This I now know to have been an error, as I 
have succeeded in making a true graphite, as determined 
by Brodie's process of conversion into graphitic oxide, 
of a very pure lampblack, and the resultant graphite to 
the eye appears to be non-graphitic carbon, and is 
entirely devoid of unctuousness or lustre. I now know, 
as the results of my prolonged experiments, that it is 
possible to produce a true graphite ranging from a harsh, 
non-unctuous, lustreless character to one of extreme 
unctuousness, softness and great lustre, the degree of 
the latter characteristics being governed by the amount 
of metallic substances, such as oxide of iron, silica, etc., 
that are associated with the non - graphitic carbon 
previous to its conversion into graphite. The first 
commercial graphitic products which I produced were 
electrodes for electrochemical work, and as I then 
believed that only carbon having a metallic lustre and 
unctuous character were graphitic, I had the manu¬ 
facturers of the non-graphitic carbon electrodes mix with 
the carbon of which they were formed two to five per 
cent, of oxide of iron, and these articles, after having 
been subjected to the temperature of my electric furnace, 
were found to be slightly unctuous and of a lustrous 
character. 

It is possible to produce practically chemically 
pure carbon by our methods, but the cost increases as 
this condition is approached, and for commercial 
purposes the purity of 99.5 per cent, is adopted for 
electrodes for use in electrochemical and electrometal¬ 
lurgical work, while for paint pigment, dry battery filler, 
and kindred uses, 92 per cent, is the standard. When 
it is remembered that a good quality of natural graphite 
contains but 85 percent, carbon, while much of that sold 
in the market runs as low as 45 per cent., it will be 


page six 


appreciated that our product is unique. For electrical 
work it is almost ideal. A rod or bar of this graphite is 
graphite throughout. It is not composed of small 
graphite particles held together by a binding agent; it 
can be cut, planed, tapped and threaded like a metal; 
its electrical conductivity is about four times that of a 
similar sized rod of non-graphitic amorphous carbon. 
Its rate of disintegration in electrochemical work is very 
slow; in some lines of work its life being twelve times 
that of the non-graphitic variety of carbon. 

The International Acheson Graphite Company now 
has a plant equipped with 3,000 electrical horse-power, 
and during 1907 produced over 3,000,000 pounds each 
of graphite electrodes, and what is termed bulk graphite, 
made principally from anthracite coal. 

During the latter part of the summer of 1899, I 
became interested in the direct reduction of silicon and 
one of my early experiments was to intimately mix, in 
fact rub together, fine, soft, pure graphite and powdered 
silica, so proportioned as to provide the necessary 
carbon for the reduction. The quantity, distribution, 
and conductivity of the graphite was sufficient to carry 
the necessary current. After the current had been 
passed for some time, the furnace cooled and opened, a 
small quantity of metallic silicon was found disseminated 
in and held as distinct particles throughout a loose, bulky 
mass of a greenish - grey substance. The commercial 
manufacture of silicon is now one of the departments of 
The Carborundum Company. The loose fluffy character 
of the material in which I found the silicon, together 
with the knowledge that it had been formed, or at least 
existed, in the path and at the temperature of the reduc¬ 
tion of silicon, caused me to immediately recognize the 
fact that it was what might be termed a highly refractory 
body. This discovery was followed by much analytical 
and experimental work. The substance was found to be 
composed of silicon, carbon and oxygen of varying 
proportions, a typical formula being SisC20. It was 
found to be amorphous, inert to both acid and basic 
slags, insoluble in melted iron, self-bonding when 


page seven 


pressed tightly together, and heated to about 2500 
degrees F., and absolutely infusible, its inevitable ' 
destruction occuring as decomposition at a very high but 
as yet undetermined temperature, the silicon, oxygen, 
and a part of the carbon passing away as vapor or gas, 
while a part of the carbon remains as graphite occupying 
the space of the destroyed body, which I have named 
Siloxicon, from the words silicon and oxygen. 

I think that it was in the latter part of the year 1903 
I conducted a few experiments on the direct reduction of 
metallic oxides, particularly alumina, and I succeeded 
in making a direct reduction and secured some small 
quantities of aluminum, by making a theoretical mixture 
of carbon and alumina in the proportions appropriate for 
the exact reduction and placing this mixture around and 
about a tube of Carborundum in which was a conducting 
core of carbon, which was highly heated by an electric 
current. The operation requires great nicety in the 
proportioning of the parts, and it is difficult to avoid the 
introduction of a small amount of silicon from the tube 
of Carborundum. 

The foregoing practically covers my experimental 
researches as conducted with the electric furnace, and I 
shall now devote a little attention to a description of 
what I think is a very interesting line of research that 
was the result of my efforts to develop into commercial 
form one of the products produced by me in the electric 
furnace. 

Having worked out the details in the manufacture 
of an artificial graphite, one much purer than the natural 
products, and being familiar with the fact that there was 
annually imported into the United States from Ceylon 
approximately $1,000,000 worth of graphite to be used 
in the manufacture of crucibles for the metal industries, 
it was my desire to secure a portion of that large trade, 
and, with that object in view, I, in 1901, entered into a 
series of experiments to determine the value of my 
graphite as a crucible body. It was not successful for 
three primary reasons : Its very purity was detrimental, 
as I found that a small percentage of impurity in the 


page eight 


graphite retards its oxidation and prolongs the life of the 
crucible; the artificial product was wanting in the fibrous 
character as found in the Ceylon graphite; and it was 
not sufficiently compact and exposed a very much larger 
surface to oxidation than was the case with the natural 
graphite. These experiments on crucible making led 
me, however, into a study of clays, and what I learned 
may be briefly stated as follows: 

1st. The American manufacturers of graphite cru¬ 
cibles imported from Germany the clay used by them 
as a binder of the graphite entering into the crucibles. 

2nd. The German clays are much more plastic and 
have a greater tensile strength than American clays of 
very similar chemical composition. 

3rd. Residual clays — those found at or near the 
point at which the parent feldspathic rock was decom¬ 
posed — are not in any sense as plastic or strong as the 
same clays are when found as sedimentary clays at a 
distance from their place of origin. 

4th. Chemical analysis failed to account for these 
decided differences. 

I reasoned that the greater plasticity and tensile 
strength as found in the sedimentary clays were imparted 
to them during the period of transportation from the 
place of their origin to their final beds, and not believing 
it could be attributed to the water which carried the 
clay, I looked to the impurities in the water, and these 
would consist largely of the washings of the forests. I 
made several experiments on clay with extracts of plants, 
tannin being one of them, and I found a moderately 
plastic, weak clay, when treated with a dilute solution 
of tannic acid, was increased in plasticity, made stronger 
—in some cases as much as 300 per cent, in the sun- 
dried condition, required but 60 per cent, as much water 
to produce a given degree of fluidity, was caused to 
remain suspended in water, and made so fine that it 
would pass through a filter paper. 

These effects seemed remarkable, and I thought that 
they might be of considerable vise in clay working, and 
knowing that clay working was one of the most ancient 


page nine 


\ 


of arts and very extensive in practice, I wondered if this 
effect were not known to clay workers. I made a search 
of all available literature, and only one reference could I 
find to the use of vegetable matter in clay working, and 
that was in the Bible, where we are told that the children 
of Israel, under the instructions of the Egyptians, used 
straw in the making of brick, and we are further told 
that they successfully substituted stubble for the straws 
The fibre of the straw is very weak, not nearly so 
valuable as a mechanical bond as many other vegetable 
fibres that were probably available to the Egyptians, 
and I thought its use must have been for another reason. 
Straw contains no tannin, so that if the effect that I had 
obtained with the tannin was due to tannin only, it was 
not likely to be produced by the extract of straw. I 
boiled some oat straw in water and found that it dis¬ 
solved to approximately 50 per cent, of its weight, and 
when clay was treated with this extract, I found it acted 
like tannin. Having determined this fact, I now thought 
that the Egyptians must certainly have been familiar 
with this effect, and in that belief I called clay so treated 
and dried “ Egyptianized Clay.” I have in this bottle 
water carrying clay in suspension, the clay having been 
masticated with a little water and extract of straw in an 
amount of less than one per cent, of the weight of the 
clay. I will fill two test tubes (Figures 1 and 2) with a 
portion of the contents of the bottle, and after adding a 
little common salt (chloride of sodium) to one tube 
(Fig. 1) place them before you to be used for a future 
demonstration. 

Having failed to secure the crucible trade for my 
artificial graphite, I now looked about for another 
possible field, and knowing that natural graphites were 
used to some extent in lubrication, and believing that 
this field might be greatly enlarged with a suitable 
product, I looked with envy on this possible application. 
My artificial graphite which I had up to that time pro¬ 
duced was not sufficiently soft or unctuous, being of 
rather a hard character and unsuitable for lubrication. 
Occasionally, however, small pieces of graphite would 


page ten 

















































































































































































be removed from the electric furnace of a character 
approaching that desired, and this led me to believe that 
it might be possible to find at some place in the world a 
natural deposit of carbonaceous material suitable for the 
manufacture of an unctuous graphite. I made a canvass 
of both North America and Europe in search of such a 
deposit. The best results were secured with an anthra¬ 
cite coal I brought from Ireland, but even this was not 
sufficiently good. In 1906, while making an experiment 
in the electric furnace, having in view the production of 
a product entirely foreign to graphite, I found in the 
output from the furnace a small amount of a very pure 
soft, unctuous graphite—the very material I had been in 
search of for five years. This discovery resulted in the 
development of methods for the manufacture of a high 
grade unctuous graphite from the refuse matter of the 
anthracite coal mines—the large culm piles of Penn¬ 
sylvania. The fixed carbon in these piles is approxi¬ 
mately 80 per cent., and this is too pure for the process, 
and I therefore add sand or other mineral matter to the 
pulverized culm to lower the fixed carbon content to 60 
per cent. This mixture is then placed in the furnace 
and brought to a sufficiently high temperature to 
volatilize all the impurities associated with the carbon, 
the resultant product being a soft^ unctuous graphite 
with a purity of over 99 per cent, carbon, I recently 
having seen in my laboratory one analysis that showed a 
carbon content of 99.82 per cent. 

Having now succeeded in manufacturing a graphite 
eminently suitable for lubrication, the next problem was 
to make it available for that purpose. Mixed with 
greases, it was easy to apply, but I wished it to enter 
the entire field of lubrication as occupied by oil, and to 
accomplish this it was essential that it remain suspended 
in a liquid. In my first efforts to suspend it in oil, I 
met the same troubles encountered by my predecessors 
in this line of work, it would quickly settle out of the 
oil, obeying the same laws governing the natural 
product. 


page eleven 


In the latter part of 1906, the thought occurred to 
me that tannin might have the same effect on graphite 
that it did on clay. I tried it with satisfactory results, 
the effect being obtainable with the natural graphites as 
found in the Ticonderoga and Ceylon varieties, and with 
the artificial product as found in Acheson-Graphite. It 
was more easily and cheaply produced when the soft, 
unctuous variety of my graphite was used, this kind 
being composed of pseudomorphs of carbide crystals, 
which had been decomposed in the electric furnace, the 
resultant graphite being very loose, porous and readily 
disintegrated. The effect was produced by masticating 
the graphite in the disintegrated form with a water 
solution of tannin, the amount of tannin being from 3 to 
6 per cent, by weight of the graphite treated. I found 
that while the effect may be produced in a very satis¬ 
factory way with distilled water, the waters as found in 
lakes, rivers, deep wells, etc., are improved by the 
addition of a trace of ammonia. 

I have operated a masticator continuously for one 
month, without interruption, the machine having been 
charged with a paste composed of graphite and water 
containing a small amount of tannin, and I afterward 
found that about 30 per cent, of the graphite would 
remain suspended apparently for all time, not having 
shown any disposition to settle for a period covering 
months. I have here a bottle containing water and 
suspended graphite, in a condition that would, I believe, 
be called by the chemists colloidal,” I having found it 
to be precipitated by an electrolyte, as is the case with 
colloids, but this word to me is wanting in significance, 
and seems rather to be solely the name of a state, and 
conveys no conception of the real condition of the body 
that is in suspension. I have adopted the name “defloc- 
culated.” This is a new word that is not to be found in 
the dictionary. Flocculation, however, is, and in the 
Century dictionary I find it defined, as applied to 
Chemistry and Physics, as “The union of small particles 
into granular aggregates or compound particles of larger 
size.” If to this word we add the prefix “de,” we have 


page twelve 



Fig. 4 


Fig. 3 
























a word that would have the meaning of the undoing or 
resolving of the compound particles into their final 
condition. I believe the body to be actually reduced to 
the molecular form, as I cannot conceive that the process 
of subdivision would cease at any definite point previous 
to the final subdivision to that condition. When the 
subdivision has been carried to this molecular state, the 
body is apparently free from the law of gravitation as 
we know it as applied to larger masses, and we have 
here graphite, which weighs approximately two and one- 
fourth times that of the water in which it is suspended, 
remaining indefinitely in suspension without any apparent 
disposition to seek a lower level. Is it not possible that 
to be colloidal is to be molecular, and to be molecular is 
to be less subject to the law of gravitation ? We know 
that colloidal gold weighing more than twenty times that 
of the water in which it is suspended will remain 
apparently indifferent to gravitation. We are familiar 
with the diffusion of gases, thus we know carbonic acid 
gas, although much heavier than air, will become diffused 
through the air, but if a volume of this gas be collected 
en masse as in a balloon, we find that it is subject to the 
law of gravitation and will immediately seek a lower 
level. 

I will now pour this black fluid through a filter- 
paper. Figure 3 shows a glass funnel containing a fine 
filter-paper resting in a test tube. In the tube below the 
funnel is the black liquid, which has passed through the 
filter-paper. This liquid is water containing 0.2 of one 
per cent, deflocculated Acheson-Graphite. I have found 
that the addition of a very minute amount of hydro¬ 
chloric acid to the water containing deflocculated graphite 
causes the contained graphite to flocculate, “unite 
its particles into granular aggregates or compound 
particles of larger size,” and it will no longer pass 
through the paper. Figure 4 shows, as in the former 
case, the funnel, filter-paper and test tube, but now in 
the lower part of the tube, below the filter, we find a 
clear liquid, this being the water in which the defloccu¬ 
lated graphite was formerly suspended, the graphite now 


page thirteen 


being caught entirely in the filter-paper above as the 
result of having being flocculated by the addition of a 
drop of acid. It will be noticed that the filter-paper in 
Figure 3 is black on the outside, this having being pro¬ 
duced by the deflocculated graphite passing through the 
paper, whereas the filter-paper, as shown in Figure 4, 
remains white on the outside, the graphite not having 
passed through its body. 

The fact of its having passed through the filter- 
paper, a paper designed to arrest any solid matter, 
leaves no doubt in our minds of the impossibility of 
separating the graphite from the water while in this 
condition, by ordinary filtration. I have, however, 
succeeded in separating the graphite and water by 
filtration, using a film of rubber as a medium. The 
possibility of separation is very clearly shown by the 
following little experiment. I will fold on itself a piece 
of filter-paper, and placing the folded paper over the 
mouth of a small vial containing water and deflocculated 
graphite; the vial is then inverted for a few moments. 
Removing and unfolding the paper, it is seen that the 
black liquid passed through the paper four times. On 
holding the paper between your eye and a source of light, 
it is seen that surrounding each of the black spots is a 
circle of wet paper perfectly colorless—(Figure 5), two 
substances have passed through the paper; one black' 
and one colorless. In a few minutes the white ring will 
have disappeared by reason of the evaporation of tfie 
water. By the use of a film of rubber, I remove the 
major part of the water and obtain a stiff paste of 
graphite and water. If this paste be dried of its water 
content, the graphite becomes a self-bonded mass, like a 
sun-dried clod of clay. I have succeeded in replacing 
the water with oil without allowing the graphite to 
become dry, obtaining a graphite oil paste, and when 
this is added to lubricating oil in an amount to give a 
graphite content equal to 0.35 of one per cent, of the 
weight of the oil, a truly wonderful lubricant is produced. 

Deflocculated graphite possesses the remarkable 
power of preventing the water in which it is suspended 


page fourteen 

























. 











from rusting or corroding iron or steel. This character¬ 
istic will unquestionably make it of great value for some 
uses, and while, as yet, little has been done to explore 
the field, some work has already been accomplished in 
using it as a cutting compound in screw cutting, and I 
have been advised by one large manufacturer that the 
results obtained showed it to be equal or superior to lard 
oil when the water was carrying as little as one-half of 
one per cent, of its weight in graphite. 

I have found that deflocculation is obtainable not 
only with tannin and extract of straw, but I have also 
produced it with catechu and the extracts of sumac, oak 
bark, spruce bark, tea leaves, and a solution of dextrine, 
and this list might be much extended. It may be 
remarked that all these substances, with the exception 
of straw and dextrine, contain tannic acid, and early in 
my experiments I thought tannin was the active agent, 
but in view of my later work it seems not so. 

I have produced the effect not only on clay and on 
graphite, but also on amorphous silica, alumina, lamp¬ 
black, and my new electric furnace product, Siloxicon, 
and it would seem that this list might be very much 
extended also. Indeed, it would seem that we might 
take it as an established law applying to all non-metallic 
amorphous bodies insoluble in water. When it be 
remembered how broadly scattered over the face of the 
earth are these amorphous inorganic bodies and these 
active organic agents, it is difficult to grasp to what 
extent this effect may be utilized in the economy of 
Nature—the effect of the organic acting upon the in¬ 
organic. Unquestionably it is this action that prepares 
the clay for the potter’s use. May it not play an 
important part in the process of the preparation of plant 
food ? 

Some months ago while crossing the Mississippi 
river at St. Louis, I looked down from the car window 
and saw the great muddy stream sweeping by to the 
Gulf, and having fresh in my mind the deflocculation of 
non-metallic amorphous bodies, it occurred to me that 
possibly the matter suspended in the water was in a 


page fifteen 


Y 

deflocculated condition, and I remembered that I had 
been told that nearly, if not quite all of this muddy water 
came out of the Missouri river from the great plains of 
the Middle West, and further, that the water did not 
clear during its entire course of some hundreds of miles, 
but that none of the muddy water was found at any great 
distance from its entry into the salt waters of the Gulf, 
the suspended material being deposited at the mouth of 
the river, there forming the great bars of the Mississippi. 
I also recalled the formation of the great delta of the 
Nile, and I felt quite convinced, without an experiment, 
that the material was deflocculated and in a colloidal 
condition, and became flocculated and settled on coming 
into contact with the electrolyte—salt water. I have not 
had an opportunity to make any investigations of the 
waters of the Mississippi, but I have to the best of my 
ability artificially produced what seems to me to be 
similar conditions. 

Referring again to the two test tubes filled with 
muddy water, you see the tube (Figure 6) to which I 
added the salt, is nearly clear, the clay being at the 
bottom. The clearing of the water is a matter of time, 
and I know from former experiments that it would in a 
few hours be perfectly clear. The water in the tube 
(Figure 7) has remained mudd}^. This experiment, I take 
it, explains perfectly why the muddy waters of the 
Mississippi, Nile and other rivers, precipitate their 
suspended solid matter when they come in contact with 
salt water, and shows how the great bars and deltas are 
formed. 

I have continuously referred to the act of defloccu¬ 
lation as an “ effect.” I know of no law, either chemical 
or physical, that will account for the results produced, 
and we are therefore compelled to define it as an ‘‘effect ” 
—“a result produced by a cause.” 













































LIBRARY OF CONGRESS 



0 033 266 790 J 


